Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754551Ab1DDMRT (ORCPT ); Mon, 4 Apr 2011 08:17:19 -0400 Received: from cantor2.suse.de ([195.135.220.15]:60884 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752611Ab1DDMRS (ORCPT ); Mon, 4 Apr 2011 08:17:18 -0400 Message-ID: <4D99B6CC.7080707@suse.cz> Date: Mon, 04 Apr 2011 14:17:16 +0200 From: Michal Marek User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101206 SUSE/3.1.7 Thunderbird/3.1.7 MIME-Version: 1.0 To: Artem Bityutskiy Cc: linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, Paulo Marques Subject: Re: [PATCH 2/2] kbuild: move KALLSYMS_EXTRA_PASS from Kconfig to Makefile References: <1301913651-9055-1-git-send-email-dedekind1@gmail.com> <1301913651-9055-2-git-send-email-dedekind1@gmail.com> In-Reply-To: <1301913651-9055-2-git-send-email-dedekind1@gmail.com> Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3443 Lines: 75 On 4.4.2011 12:40, Artem Bityutskiy wrote: > From: Artem Bityutskiy > > At the moment we have the CONFIG_KALLSYMS_EXTRA_PASS Kconfig switch, > which users can enable or disable while configuring the kernel. This > option is then used by 'make' to determine whether an extra kallsyms > pass is needed or not. > > However, this approach is not nice and confusing, and this patch moves > CONFIG_KALLSYMS_EXTRA_PASS from Kconfig to Makefile instead. The > rationale is below. > > 1. CONFIG_KALLSYMS_EXTRA_PASS is really about the build time, not > run-time. There is no real need for it to be in Kconfig. It is > just an additional work-around which should be used only in rare > cases, when someone breaks kallsyms, so Kbuild/Makefile is much > better place for this option. > 2. Grepping CONFIG_KALLSYMS_EXTRA_PASS shows that many defconfigs have > it enabled, probably not because they try to work-around a kallsyms > bug, but just because the Kconfig help text is confusing and does > not really make it clear that this option should not be used unless > except when kallsyms is broken. > 3. And since many people have CONFIG_KALLSYMS_EXTRA_PASS enabled in > their Kconfig, we do might fail to notice kallsyms bugs in time. E.g., > many testers use "make allyesconfig" to test builds, which will enable > CONFIG_KALLSYMS_EXTRA_PASS and kallsyms breakage will not be noticed. > > To address that, this patch: > > 1. Kills CONFIG_KALLSYMS_EXTRA_PASS > 2. Changes Makefile so that people can use "make KALLSYMS_EXTRA_PASS=1" > to enable the extra pass if needed. > 3. By default KALLSYMS_EXTRA_PASS is disabled and if kallsyms has issues, > "make" should print a warning and suggest using KALLSYMS_EXTRA_PASS > 4. Add "make help" entry for KALLSYMS_EXTRA_PASS > > Signed-off-by: Artem Bityutskiy > Cc: Paulo Marques > Cc: Michal Marek > --- > Makefile | 13 ++++++++----- > init/Kconfig | 12 ------------ > 2 files changed, 8 insertions(+), 17 deletions(-) > > diff --git a/Makefile b/Makefile > index ba7a55c..b66a43a 100644 > --- a/Makefile > +++ b/Makefile > @@ -797,15 +797,16 @@ ifdef CONFIG_KALLSYMS > # o The correct .tmp_kallsyms2.o is linked into the final vmlinux. > # o Verify that the System.map from vmlinux matches the map from > # .tmp_vmlinux2, just in case we did not generate kallsyms correctly. > -# o If CONFIG_KALLSYMS_EXTRA_PASS is set, do an extra pass using > +# o If 'make KALLSYMS_EXTRA_PASS=1" was used, do an extra pass using > # .tmp_vmlinux3 and .tmp_kallsyms3.o. This is only meant as a > # temporary bypass to allow the kernel to be built while the > # maintainers work out what went wrong with kallsyms. > > -ifdef CONFIG_KALLSYMS_EXTRA_PASS > -last_kallsyms := 3 > -else > last_kallsyms := 2 > +ifeq ("$(origin KALLSYMS_EXTRA_PASS)", "command line") I would drop the origin check here. We use it for single-letter variables that could be used outside the kernel with a different meaning, but if you export KALLSYMS_EXTRA_PASS, then you certainly mean the kernel's KALLSYMS_EXTRA_PASS. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/